封闭体系有机质与有机碳氢氮恢复动力学研究

在封闭体系的条件下,对典型的Ⅰ、Ⅱ、Ⅲ型干酪根在热演化过程中的损失进行生烃动力学研究,获得了Ⅰ、Ⅱ、Ⅲ型干酪根的总量、有机碳、氢以及氮质量损失动力学参数。用Kinetics软件计算了封闭体系干酪根有机碳丰度、氢碳原子比和氮碳原子比的恢复系数。认为在对高成熟—过成熟干酪根进行生烃评价时,Ⅰ、Ⅲ型干酪根残余有机碳丰度需要进行恢复,而Ⅱ型干酪根残余有机碳丰度不需要恢复。三种类型干酪根的氢碳原子比均需要进行恢复。     

Analysis of trends in annual streamflow to the Arctic Ocean

There is increasing interest in the magnitude of the flow of freshwater to the Arctic Ocean due to its impacts on the biogeophysical and socio‐economic systems in the north and its influence on global climate. This study examines freshwater flow based on a dataset of 72 rivers that either directly or indirectly contribute flow to the Arctic Ocean or reflect the hydrologic regime of areas contributing flow to the Arctic Ocean. Annual streamflow for the 72 rivers is categorized as to the nature and location of the contribution to the Arctic Ocean, and composite series of annual flows are determined for each category for the period 1975 to 2015. A trend analysis is then conducted for the annual discharge series assembled for each category. The results reveal a general increase in freshwater flow to the Arctic Ocean with this increase being more prominent from the Eurasian rivers than from the North American rivers. A comparison with trends obtained from an earlier study ending in 2000 indicates similar trend response from the Eurasian rivers, but dramatic differences from some of the North American rivers. A total annual discharge increase of 8.7 km³/y/y is found, with an annual discharge increase of 5.8 km³/y/y observed for the rivers directly flowing to the Arctic Ocean. The influence of annual or seasonal climate oscillation indices on annual discharge series is also assessed. Several river categories are found to have significant correlations with the Arctic Oscillation, the North Atlantic Oscillation, or the Pacific Decadal Oscillation. However, no significant association with climate indices is found for the river categories leading to the largest freshwater contribution to the Arctic Ocean.     

Abundance and distribution of ichthyoplankton in the upwelling zone off Oregon during anomalous El Niño conditions

The abundance and distribution patterns of nearshore ichthyoplankton were investigated during a year of anomalously high sea temperatures off Oregon. Samples collected from 2 to 18 km offshore from April through September of 1983 showed increased occurrences and higher abundances of taxa usually found at distances offshore of 37 km in other years. The dominant species collected, comprising more than half of the total larval fish abundance, was the northern anchovy (Engraulis mordax). Larval anchovy have rarely been collected inshore in previous studies. Many of the dominant taxa normally found inshore, especially osmerids, were present in reduced numbers in 1983. Changes in the hydrographic conditions associated with onshore surface drift and reduced summer upwelling during the 1983 El Niño could explain the distributional patterns observed. The warm inshore waters apparently provided a substantial spatial and temporal expansion of the spawning habitat for E. mordax.     

Structural aspects of the surf-zone fish assemblage at King's Beach,Algoa Bay,South Africa: Short-term fluctuations

Short-term changes in the King's Beach surf-zone fish assemblage were investigated by means of two 24 h studies (January and August 1979), and by seine netting on three consecutive days at both high and low tide. They revealed considerable variation in the fish assemblage over a 24 h period. Four species: the gorrie, Pomadasys olivaceum; the mullet, Liza richardsoni; the streepie, Sarpa salpa; and the sand steenbras, Lithognathus mormyrus, dominated the catches of both 24 h studies. The number of species caught reached a peak just after twilight. Trends in other community parameters were not consistent for these two sets of data. Considerable variation in dominant species, numbers and species diversity indices was observed from day to as well as between high and low tide. Shortterm fluctuations in various community parameters often exceeded the long-term variability observed in a seasonal study of this fish assemblage.     

Structural aspects of the surf-zone fish assemblage at King's Beach,Algoa Bay,South Africa: Long-term fluctuations

Regular collections of fish were obtained from the surf-zone at King's Beach, Algoa Bay. A total of 3970 fish, representing 50 species was caught with a coarse net and 16 857 fish, representing 37 species, were caught with a fine net. Predominant species were the blacktail, Diplodus sargus; the sand steenbras, Lithognathus mormyrus; the mullet, Liza richardsoni; the gorrie, Pomadasys olivaceum; the white stumpnose, Rhabdosargus globiceps; the sandshark, Rhinobatos annulatus; and the streepie, Sarpa salpa. No seasonal trends were discernible in the overall abundance or species diversity. The species composition of the dominant component of the fish assemblage varied considerably. This indicated instability in the community structure and cast doubts on the applicability of a classic community concept and the use of diversity indices. Neither classification nor correspondence analysis were of any use in identifying a characteristic species component. Multiple regression analysis indicated that short-term variations in wind conditions might be a primary determinant of fluctuations in abundance. The lack of seasonality in the community parameters may reflect the fact that short-term variability masks seasonal perturbations.     

1980-2020年山西省极端降水的研究

基于1980-2020年山西省109个气象观测站点的逐日降水资料,选取10个极端降水指数,采用气候倾向率、相关分析、因子分析、R/S预测方法等方法,对山西省极端降水进行了时空分布的研究,以期为山西省的气候变化、生态环境保护、防灾减灾、气象服务工作提供参考依据,结果表明：(1)从时间尺度来看,1980-2020年期间,山西省极端降水的强度和极值都有明显增加,连续干旱日数和连续湿日日数呈下降趋势,其余均表现出不同程度的增加,其中年总降水量增加幅度最明显;从空间尺度来看,年总降水量、降水强度、降水频率、极值均为从西北向东南逐渐增多,空间差异较明显;从各站点的空间分布来看,北部和中部地区的极端事件增加最显著,北部地区的干旱日数仍以增加趋势为主,连续湿日日数气候倾向率的空间差异较大,中部地区站点显著增加,南北部以减少趋势为主;(2)基于相关分析方法表明各极端降水指数(除干旱日数外)与年总降水量都有很好的相关关系,强降水量和极强降水量对年总降水量的贡献值呈现出增加趋势;采用因子分析方法提取了3个公共因子,方差贡献率累计达到了87％,可以看出极端降水强度和降水量指数在对极端降水方面影响较大;利用R/S分析法可以得到年总降水量、中雨日数、大雨日数、最大5日降水量这几个指数未来呈现弱减少趋势,而干旱日数仍为减少趋势,连续湿日日数为持续弱增加趋势。总体看来,山西省极端降水近年来呈现出增加趋势,在空间分布有明显差异。     

Uplift along the western margin of the Deccan Basalt Province: Is there any geomorphometric evidence?

In line with the passive margin landscape evolutionary model in vogue, sustained erosion and long-distance retreat of the Western Ghat escarpment are widely considered to be the results of erosionally-driven isostatic uplift since Tertiary by many workers. Others have postulated or adduced evidence for strong neotectonic activity in the Ghat region. An obvious question in this regard is whether there is any geomorphometric evidence in support of this widespread view? In order to test the hypothesis of ongoing post-rift fexural uplift or neotectonic activity in the western Deccan Basalt Province (DBP), geomorphometric analysis was carried out and commonly used geomorphic indices of active tectonics (GAT) were derived for 30 selected river basins on both sides of the Western Ghat. SRTM-DEM data and ArcGIS were used to derive the indices. Tectonic geomorphic analysis based on five proxy indicators suggests that the differences in GAT indices, both along strike and across the Western Ghat, are statistically insignificant. The index values are nowhere close to the GAT values typically associated with drainage basins affected by active tectonics and deformation. Mapping of the indices reveals lack of discernable trends. The adduced results indicate that the western DBP belongs to the class of relatively low tectonic activity.     

Evaluation of forest fire on Madeira Island using Sentinel-2A MSI imagery

A forest fire started on August 8th, 2016 in several places on Madeira Island causing damage and casualties. As of August 10th the local media had reported the death of three people, over 200 people injured, over 950 habitants evacuated, and 50 houses damaged. This study presents the preliminary results of the assessment of several spectral indices to evaluate the burn severity of Madeira fires during August 2016. These spectral indices were calculated using the new European satellite Sentinel-2A launched in June 2015. The study confirmed the advantages of several spectral indices such as Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), Normalized Burn Ratio (NBR) and Normalized Difference Vegetation Index (NDVIreXn) using red-edge spectral bands to assess the post-fire conditions. Results showed high correlation between NDVI, GNDVI, NBR and NDVIre1n spectral indices and the analysis performed by Copernicus Emergency Management Service (EMSR175), considered as the reference truth. Regarding the red-edge spectral indices, the NDVIre1n (using band B5, 705 nm) presented better results compared with B6 (740 nm) and B7 (783 nm) bands. These preliminary results allow us to assume that Sentinel-2 will be a valuable tool for post-fire monitoring. In the future, the two twin Sentinel-2 satellites will offer global coverage of the Madeira Archipelago every five days, therefore allowing the simultaneous study of the evolution of the burnt area and reforestation information with high spatial (up to 10 m) and temporal resolution (5 days).     

皖南国际文化旅游示范区文化资源丰度评价

以皖南国际文化旅游示范区为研究对象,从文化与旅游融合发展的视角,通过构建区域文化资源丰度评价指标体系,对示范区各地市文化资源丰度进行测度,得出如下结论：皖南国际文化旅游示范区中黄山、安庆、宣城、池州4市的文化资源赋存丰度为优级;马鞍山、芜湖市为良好;铜陵市为差级,优级区主要集中在南部和东西部,南北差异明显。从文化资源组合状况来看,黄山市文化资源组合状况最好,品牌资源众多,开发潜力巨大;其次是宣城、安庆和池州3市,资源类型齐全,组合状态较好;马鞍山、铜陵和芜湖3市较差,类型相对单一,开发难度较大。建议政府部门及旅游业界据此结果,科学评估文化资源的价值和开发方向,探索旅游开发的有效模式,推动文化与旅游融合发展,实现示范区优秀文化传承与创新。     

广西金牙金矿床中饱和烃丰度分布特征及其意义

对广西金牙金矿床的可溶有机质族组成和气相色谱分析表明，矿体饱和烃的丰度低于围岩，矿体与围岩总抽提物所气相色谱图亦明显不同，尤其是甲醇－丙酮－苯抽提物的区别更明显，矿体与围岩饱和烃丰度的差异为分析有机质在金矿形成过程中的作用提供了线索，对其意义进行了讨论。